Advice for use of ND filter on TLR

Rachelle · Feb 28, 2023

Hello, I'm a new owner of a Mamiya C330 and also new to shooting on TLR cameras. I'm well experienced with shooting on film and rangefinders. My film rangefinders have built in light meters, thus, making it more feasible to work with a variable ND filter. My 1 - 8.66 f-stop filter does not indicate numerical measurements for each f-stop. Instead it has gradual bar graphics for f-stop changes.

My dilemma is using an existing variable ND filter on a camera that lacks a light meter. My gut tells me that using this filter for different f-stops will not be practical on the Mamiya C330. Am I right, and I should use fixed f-stop filters? This would make it easier to calculate with more accuracy?

Thanks in advance for the advice you can offer. I tried researching extensively on this topic. I'm very excited to be learning and shooting on a TLR.

Philippe-Georges · Feb 28, 2023

To my personal experience, there ar about 3 ways to handel this:
- Get Mamiya's prism finder with an incorporated lightmeter and mount a second ND filter, set to the same value, on the viewfinder lens, as this lightmeter meters through that lens.
- Set the ND filter as wanted and then hold it in front of your handheld lightmeter and meter through it.
- Find the correct exposure by guessing, or else by trial and error and/or (expanded-) bracketing.

BrianShaw · Feb 28, 2023

Fixed ND...

xkaes · Feb 28, 2023

It's unclear how you plan to meter with the TLR, but I'd suggest metering a bright white wall with your "available metering method" -- then add the ND filter. Then mark the side of the filter according to the meter reading -- using paint, notching or wudeva..

grahamp · Feb 28, 2023

I'd just calibrate the variable ND to full stops using one of your TTL metering cameras, and then adjust your hand meter reading accordingly. Swapping filters from the viewing lens to taking lens (assuming you have one of the Mamiya metering finders) without displacing the filter setting seems more fiddly and time consuming than necessary. But then I'm not addicted to ND filters

Does this device have a fixed front filter thread? I'm curious about how it is adjusted with a lens hood.

Rachelle · Feb 28, 2023

Philippe-Georges said:
To my personal experience, there ar about 3 ways to handel this:
- Get Mamiya's prism finder with an incorporated lightmeter and mount a second ND filter, set to the same value, on the viewfinder lens, as this lightmeter meters through that lens.
- Set the ND filter as wanted and then hold it in front of your handheld lightmeter and meter through it.
- Find the correct exposure by guessing, or else by trial and error and/or (expanded-) bracketing.

Intriguing idea that I didn’t think of - hold the filter in front of the handheld lightmeter. I’m curious how this will work for me and will try. Thanks for suggesting!

I opted to first purchase a magnifier because sometimes my ageing eyes require a bit more help for precision. I’ve been reluctant to purchase another accessory because they are selling for high prices and working CDS prism is rare for C series. Still contemplating.

Rachelle · Feb 28, 2023

BrianShaw said:
Fixed ND...

I’m leaning towards this option. A lower cost approach due to rare and pricey CDS prism finders these days. Thanks for your input.

Rachelle · Feb 28, 2023

xkaes said:
It's unclear how you plan to meter with the TLR, but I'd suggest metering a bright white wall with your "available metering method" -- then add the ND filter. Then mark the side of the filter according to the meter reading -- using paint, notching or wudeva..

Currently I have a handheld meter, so I was exploring options with that approach. Fixed NDs filters seem to be a more practical and affordable solution. Even with a CDS accessory, I realised that it may be time consuming to be accurate on how I position the marks of the variable filter for both the viewing and taking lenses. It could lead to missed photo opportunities and less spontaneity.

Thanks for your feedback!

Rachelle · Feb 28, 2023

grahamp said:
I'd just calibrate the variable ND to full stops using one of your TTL metering cameras, and then adjust your hand meter reading accordingly. Swapping filters from the viewing lens to taking lens (assuming you have one of the Mamiya metering finders) without displacing the filter setting seems more fiddly and time consuming than necessary. But then I'm not addicted to ND filters

Does this device have a fixed front filter thread? I'm curious about how it is adjusted with a lens hood.

I agree - fiddly and time consuming. In my previous reply to another post on this thread, even with CDS viewing accessory it requires additional time and precision.

The lens has a thread for filter and hood. Currently I don’t have a hood with a compatible thread. The uv filters fit well. My hood for another camera lens with the same thread (46) doesn’t fit. It’s designed to fit around the lens and space is tight between the TLR lenses.

Thanks for your reply!

BrianShaw · Feb 28, 2023

Rachelle said:
I’m leaning towards this option. A lower cost approach due to rare and pricey CDS prism finders these days. Thanks for your input.

Trust me on this... the only "variable" that you'll possibly want to use on a TLR is a polarizer... and that is only because there really isn 't a "fixed" option.

Rachelle · Feb 28, 2023

BrianShaw said:
Trust me on this... the only "variable" that you'll possibly want to use on a TLR is a polarizer... and that is only because there really isn 't a "fixed" option.

Agree. I’m understanding TLR better now

Neil Grant · Feb 28, 2023

.. a CdS meter can exhibit significant 'memory' under low-light. Not what you need when using ND filters. Not sure if there ever was a metered prism. CdS porrofinder maybe. Most practical solution would be fixed ND, preferably multicoated. 49mm with a 46 to 49 step-up will cover all the C series lenses.

Rachelle · Feb 28, 2023

Neil Grant said:
.. a CdS meter can exhibit significant 'memory' under low-light. Not what you need when using ND filters. Not sure if there ever was a metered prism. CdS porrofinder maybe. Most practical solution would be fixed ND, preferably multicoated. 49mm with a 46 to 49 step-up will cover all the C series lenses.

I was not aware about the ‘memory’ issue re: CDS meters. There was no mention of a CDS prism in the Mayima manuals, but I’ve found some CDS prisms being sold, most with dysfunctional meters. I can’t verify meter function on these sales posts.

Nonetheless, I’m sold on the fixed ND as a solution. I appreciate you saving me time on investigating thread sizes for other lenses. Thank you!

xkaes · Feb 28, 2023

I get by with three ND filters -- 1f, 2f & 10f. Probably cheaper than a variable one.

MattKing · Feb 28, 2023

It would be worth your while to use the variable filter as your 8.66 stop ND - assuming that the maximum setting is well delineated.
There were no CDS metered prism finders, but there were/are CDS metered Porrofinders.

Rachelle · Feb 28, 2023

xkaes said:
I get by with three ND filters -- 1f, 2f & 10f. Probably cheaper than a variable one.

There's a brand I like that sells reasonably priced, good quality variable filters. I was skeptical at first, but found it to work well for my other cameras. Their variable ND filter is the same price of 1 ND filter. I've never found the need to go beyond 10 fstop.

Rachelle · Feb 28, 2023

MattKing said:
It would be worth your while to use the variable filter as your 8.66 stop ND - assuming that the maximum setting is well delineated.
There were no CDS metered prism finders, but there were/are CDS metered Porrofinders.

Thank you, that is good to know that there was never a CDS metered prism. I can pass along the along advice to others because items are being advertised as "CDS metered prism" or "CDS metered prism, meter does not work".

I agree, I think it's worth a try with my current variable filter at its max setting. I did find a decently priced 3 set filter kit, multi-layers of nano-coating. It costs less than 2 individually priced fixed filters.

grahamp · Mar 1, 2023

Mamiya did a CdS version of the Porrofinder (internal mirrors, not a pentaprism), and a CdS metered chimney finder (not the one with adjustable magnification). There have also been third-party adaptions of 6x6 prisms from other cameras - Kiev ones in particular, but unless they contain a self-contained match-needle type meter, they probably would not help.

The Mamiya meter finders are match needle, and the exposure is read from a dial that needs the film speed set. Then the exposure is transferred to the lens.

Rachelle · Mar 4, 2023

grahamp said:
Mamiya did a CdS version of the Porrofinder (internal mirrors, not a pentaprism), and a CdS metered chimney finder (not the one with adjustable magnification). There have also been third-party adaptions of 6x6 prisms from other cameras - Kiev ones in particular, but unless they contain a self-contained match-needle type meter, they probably would not help.

The Mamiya meter finders are match needle, and the exposure is read from a dial that needs the film speed set. Then the exposure is transferred to the lens.

Thank you @grahamp for your input. I’m hoping my handheld meter will do just fine for now and will be a way to improve my photography skills.

Perhaps I’ll stumble upon a good deal for a working metered chimney finder. It’s a rare find!

eli griggs · Mar 7, 2023

Use a fixed ND gel cut to a Bay/Series adapter size.

BrianShaw · Mar 7, 2023

eli griggs said:
Use a fixed ND gel cut to a Bay/Series adapter size.

How did you do this, Eli? Every time I tried with Rosco gels with scissors or razor knife I both scratched and fingerprinted them. Every time. If there’s a better way…

eli griggs · Mar 7, 2023

I suggest you make a press-cutter, like a biscuit cutter, but with a sharpener edge running all along the round edge.

A steel or brass tube with the same sized inside diameter as the needed filter, and, evenly belveled/sharpened into an edge.

You can also use thin sheets/pieces, of steel or brass or bronze rolled one layer thick around a down or tube and secured in it's shaped, by hose worm-ring fittings, epoxy, or silver soldered

Both Michael's and Hobby Lobby, as well as, Lowe's and Home Depot carry "K&S Precision" brass, copper, bronze pieces to do this with.

So, wear away and sharpen the the outer wall edge toward the inside.

Remove any burrs, chips, or wire remains, so the cutter can be pressed directly down to cut the gel, cookie cutter style.

A simple press can be made but a small arbor press, or press, from Harbor Freight, will do the job, or try a shooter's reloading metal cartridge press.

I do no recommend Rosco gels, because they are no made for use as camera lens filters, and prefer Kodak Gels, myself.

If you have access to a Circuit machine, you can try using a "light" grip cutting pad for holding your 'mother' material, in place, and a new blade for larger than .75 in. circles.

I have yet to try this on my machine but, if I find a three or four inch or larger Kodak or Lee gel that I can afford to experiment on, I'll give it a go and report back on the results.

Good luck, and please, show us your results .

PS: wear white tuxedo gloves or 9ml nitrile gloves, which can be found at Harbor Freight.

Do no touch your face or scratch while wearing gloves!

Advice for use of ND filter on TLR

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